Indian wildlife authorities have decided to carry out a census of tigers simultaneously in all forests across the country from October.

"To get a complete picture of the tiger situation in the country, it has been decided to have censuses simultaneously in the different forests," said Pradeep Vyas, director of Project Tiger in the Sunderbans forest, the world's largest tiger habitat.

So far, different tiger reserves had carried out censuses of the big cats according to their convenience.

But the Sariska missing tigers episode forced the central government to come up with comprehensive conservation policies, and the new census method is among them.

"The exercise will mean a more coordinated effort. Data sharing and comparative studies will become easier," Vyas continued.

The census will be spread out over a period of four months starting October.

As part of the new conservation methods, wildlife officials have also planned to put satellite-linked radio collars on tigers and build an old-age home for the big cats in the Sunderbans.

India has intensified efforts to protect its tiger population after reports in March that the entire tiger population at the Sariska tiger reserve in western India had been killed by poachers. There were 16-18 tigers in Sariska in 2004.

Animal rights activists say the story may be the same in other sanctuaries across the country where a century ago there were some 40,000 tigers, but now the number is down to just about 3,700.

Some environment groups put the number at less than 2,000.

Trade in dead tigers is illegal, but poachers still operate with impunity because a single animal can fetch up to $50,000 in the international market.

Organs, teeth, bones and penises fetch high prices in the black market, where they are used in Chinese medicine.